VIPomas Clinical Presentation

Updated: Mar 16, 2017
  • Author: Sai-Ching Jim Yeung, MD, PhD, FACP; Chief Editor: George T Griffing, MD  more...
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Presentation

History

The onset of VIPoma is insidious. The dominant symptom is profuse diarrhea despite fasting; this symptom may persist for years before the diagnosis is established. Diarrhea may be episodic initially, but it becomes continuous as the tumor progresses. The stool is typically odorless and tea-colored, without blood or mucus.

Clinical diagnosis is based on a history of approximately 10 watery stools per day. Fecal losses during fasting are at least 20 mL/kg/day but exceed 50 mL/kg/day in most cases. Fecal osmolality is entirely accounted for by twice the sum of the concentrations of sodium and potassium, indicating the electrolyte loss.

The loss of water, sodium, and chloride may lead to volume depletion, dehydration, and exhaustion among patients who are unable to replace the lost fluid and electrolytes. Weight loss and even renal failure have been reported in some patients. Excretion of large amounts of potassium and bicarbonate in the stool causes hypokalemia and non–anion gap acidosis. Hypokalemia may present as muscle cramps or weakness.

Abdominal discomfort or bloating has been reported. In a 31-case series from China, facial flushing was observed in one third of patients. [15] Other studies have also reported facial flushing, but without specifying its frequency.

One patient in China reportedly suffered from periodic backache and a rash involving the chest, back, and upper limb. These 2 symptoms occurred before or after the diarrhea, worsened over 6 years, and resolved after surgical resection.

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Physical Examination

Aside from a mildly extended abdomen, no relevant abnormalities may be apparent on physical evaluation of patients with VIPomas. However, physical examination may also reveal one or more of the following:

  • Tachycardia, decreased skin turgor, and documented weight loss (from volume depletion)
  • Muscle weakness (from marked fecal loss of potassium)
  • Hepatomegaly (if liver metastasis has occurred)
  • Facial flushing (from the vasodilatory effects of vasoactive intestinal polypeptide [VIP])
  • Profuse sweating
  • Colonic dilatation
  • Glucose intolerance

Electrolyte abnormalities (see Workup) are commonly noted.

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